High modulus fibers have been used in the production of ballistic articles and high performance composites. Examples include aramid fibers, graphite fibers, glass fibers, nylon fibers, high modulus polyethylene fibers and the like. Woven fabric from such fibers can be impregnated with heat curable resins and fabricated into shaped composites alone or in combination with other materials.
Hard laminate plates of fiberglass coated with polyester resins have been inserted into pockets of nylon jackets for body armor. Fiberglass alone has poor impact and ballistic resistance. A composite or laminate of these two materials however has high impact and ballistic resistance (Ballistic Materials and Penetration Mechanics, R. C. Laible, page 102, Elsevier Scientific Publishing Co., New York, 1980). Other resins that have been considered include polystyrene, polystyrene-polyester copolymers, polymethyl methacrylate, melamine-formaldehyde and thermosets, such as, Laminac (a trademark of American Cyanamid).
Different types of glass with varying moduli were compared including E-glass, LMLD (low modulus, low density glass), S-glass and D-glass (dielectric glass). These glasses differed in the content of calcium oxide, aluminum oxide, boron oxide, sodium oxide, potassium oxide and lead oxide.
The helmet liner insert for the classical steel helmet of World War II is a laminate of nylon fabric and a phenolic modified polyvinyl butyral resin.
A report by A. L. Alesi et al. in Army Sci. Conf. Proc., I, page 18 (1974) compared flat laminates of Kevlar fabric and phenolic polyvinylbutyral resin with laminates of LMLD fiber; XP (a highly oriented polypropylene film) and a composite of glass reinforced plastic (GRP), XP and Kevlar.
U.S. Pat. No. 4,639,387 monofilament fibers coated with a curable resin and wound on a mandrel into a plurality of layers are consolidated under heat and pressure to a unitary body.
U.S. Pat. No. 4,181,768 discloses a laminate for body armor of alternating layers of Kevlar and 6,6 nylon film bonded by heat.
U.S. Pat. No. 4,678,702 discloses a laminate of at least nine layers of Kevlar fabric and Surlyn heated to a point where the Surlyn flows into and encapsulates the Kevlar yarn.
U.S. Pat. No. 3,801,416 teaches the use of blast-resistant plates embedded in a plurality of layers of flexible blast-resistant material.
U.S. Pat. No. 3,924,038 describes a ballistic shield-protective system including ballistic nylon felt layers enclosed within a surface of ceramic or tile mounted on glass cloth and metal back plate.
U.S. Pat. No. 3,904,455 discloses a laminated fabric comprising a woven or knotted web of textile fibers reinforced by a backing of a spun bonded non-woven web.
U.S. Pat. No. 4,428,998 discloses a laminated missle shield of multiple layers of resin impregnated aramid fiber woven fabric in a rubbery matrix.
U.S. Pat. No. 4,574,105 shows a penetration resistant panel comprising plied layers of interwoven textile yarn of poly(p-phenylene terephthalamide) backed with plied layers of woven or non-woven fibers of 6,6 nylon.
U.S. Pat. No. 4,539,253 discloses prepreg fabrics comprised of a first layer of reinforced fabric coated with an epoxy resin modified with an elastomeric polymer having high impact resistance.
U.S. Pat. No. 4,738,893 provides a fiber-based structure from a plurality of layers of organic aromatic polyamide fibers bonded with intermediate layers of elastomer.
Despite the plethora of devices for ballistic protection in the prior art, there is a continuing need for more economical ones.